This is the second year of variable-rate application of fertilizer.
Before variable-rate fertilizer application:
Applied 116 to 120 pounds of 40-20-0 with the drills.
Average yield is 30 bushels.
Producer has Global Positioning System (GPS) guidance system for equipment with yield monitors (cost of guidance system was $6,000).
With variable-rate fertilization application:
Producer hired a Technical Service Provider (TSP) to provide technical expertise for variable-rate application of fertilizer.
The TSP obtained satellite imagery of growing crops a couple times a year to develop zones.
Cost of zone development was $5 to $8 per acre.
Need a three-tank air seeder to variable-rate apply nitrogen. (One tank contains the seed, one tank contains nitrogen, and the third tank has the phosphorus fertilizer. Both the nitrogen and phosphorus were applied at a variable rate.)
Producer purchased a task controller for $1,500 to variable-rate apply the fertilizer.
The fertilizer is applied with the seed in a single shovel that applies both over the six-inch opening. This shovel is a No-Till Low Disturbance Six Inch. Fertilizer cost was $1 to $2 per acre more with the variable-rate application. The fertilizer on the variable-rate applied field cost the same as the conventionally applied fields.
In 2005, five-bushel increase in yield on 500 acres, protein was 0.5 to 0.7 percent higher with a $.20 per quarter percent increase in protein per bushel premium.
In 2006, one to two bushel increase in yield and there was no premium for protein. Average yields were in the high 30’s and low 40’s for his entire crop.
General comments - Producer felt it works great on hilly fields; very little nitrogen is applied on the hill tops. In the past the hills would burn up because of the high fertilizer rate and thin soils. They had the best stands on the hill tops they have ever had. Expects a two to four bushel increase in yield for variable-rate application of fertilizer in future years with average moisture, plans to use a soils map to develop zones in the future and will do variable-rate application of fertilizer on all their land that has hilly terrain.
Cost of zone development of $5 to $8 per acre.
Cost of $1,500 task controller.
Yield increase of five bushels in year one and one- to two-bushel increase in the second year.
Protein premium of $.20 per quarter percent increase per bushel for 30 bushels in the first year and no premium in the second year, but this will vary each year.
Increased fertilizer cost of $1 to $2 per acre.
Expects a two- to four-bushel increase in yield in future years.
Develop three zones for variable application of fertilizer and do a good job of soil sampling and be sure to calibrate the yield monitor before starting harvest to get good data.
Look at the fertilizer cost per acre that you are willing to spend and then variable-rate apply the fertilizer.
500 acres is a good number of acres to start learning the variable-rate application of the fertilizer process.